Document And Entity Information - shares	6 Months Ended
	Oct. 31, 2020	Dec. 08, 2020
Document And Entity Information [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Oct. 31, 2020
Document Transition Report	false
Entity File Number	0-23248
Entity Registrant Name	SIGMATRON INTERNATIONAL INC
Entity Incorporation State Country Code	DE
Entity Tax Identification Number	36-3918470
Entity Address Address Line 1	2201 Landmeier Road
Entity Address City Or Town	Elk Grove Village
Entity Address State Or Province	IL
Entity Address Postal Zip Code	60007
City Area Code	847
Local Phone Number	956-8000
Title of 12b Security	Common Stock $0.01 par value per share
Trading Symbol	sgma
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		4,257,508
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--04-30
Document Fiscal Year Focus	2021
Amendment Flag	false
Entity Central Index Key	0000915358